Torsionally adjustable spring diving board



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TORSIONALLY ADJUSTABLE SPRING DIVING BOARD 9 Sheets-Sheet 5 Filed Oct. 31, 1963 IXYENTOR w. .J. NIGHTINGALE 3,350,093

TORSIONALLY ADJUSTABLE SPRING DIVING BOARD Filed Oct. 31, 1965 9 Sheets-Sheet 6 Oct. 31, 1967 w. J. NIGHTINGALE 3,350,093

TORSIONALLY ADJUSTABLE SPRING DIVING BOARD 9 Sheets-Sheet '7 Filed Oct. 51, 1963 INKENTOR.

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TORSIONALLY ADJUSTABLE SPRING DIVING BOARD Filed OGC. 31, 1965 9 Sheets-heet 9 H m Z? L I mm \1- I I w H I w w I I K I" I z J \g 1 w I "I I a Z Q l United States Patent 3,350,093 TORSIONALLY ADJUSTABLE SPRING DIVING BOARD William J. Nightingale, Chicago, Ill., assignor of twentyfive percent to Charles F. Voytech, Chicago, Ill. Filed Oct. 31, 1963, Ser. No. 320,344 16 Claims. (Cl. 272-66) This invention relates to diving boards and particularly to that type of diving board in which the board is rigid but is hinged to a platform for vertical swinging movement, the necessary resilience normally supplied by a flexible board being supplied in this case by separate springs actuated by the movement of the hinged board. The term board as herein sometimes used, is not limited to a structure made of wood, but'is used to designate a deck made of any'material including rigid metal structures and used as a springboard by a diver.

In my prior Patent No. 2,590,566 dated Mar. 25, 1952, for Diving Boards, there is disclosed a torsion bar spring and mounting therefor for use with a rigid hinged diving board deck. Means are disclosed therein for changing the effective length, and hence the rate or force per unit of deflection, of the torsion bar spring. The present invention is an improvement upon the torsion bar spring disclosed in my aforesaid prior patent and has among its objects the provision of a simple means for adjusting the rate of a torsion bar spring, the provision of means for replacing a torsion bar spring either with the same sized bar or with a different bar to change the deflection rate of the board; the provision of means for shielding a torsion bar spring from corrosive water either from an adjacent pool or from the elements, and the provision of a basic structure for a diving board which structure can be readily, quickly, and economically altered to provide a diving board adapted to meet specific conditions.

These and other objects of this invention will become apparent from the following detailed description of a preferred embodiment of the invention when taken together with the accompanying drawings thereof in which:

FIG. 1 is a plan view of a diving board made with a rigid diving deck and to which this invention may be readily applied;

FIG. 2 is a side elevational view of the diving board of FIG. 1;

FIG. 3 is a plan view of the board of FIG. 1 in section, the section being taken along line 33 of FIG. 2 and looking in the direction of the arrows at the ends thereof;

-FIG. 4 is an enlarged side elevational view in section of the rear portion of the diving board of FIG. 1, the section being taken along line 4-4 of FIG. 5 and looking in the direction of the arrows at the ends thereof;

FIGS. 5 and 6 are front end elevational views of the diving board of FIG. 4, showing the board in two stages of its operation, said section being taken along line 55 of FIG. 4 and looking in the direction of the arrows at the ends thereof;

FIG. 7 is a side elevational view of the diving board of FIG. 1, showing in a dot-dash outline the position of the diving deck when it is deflected a maximum amount;

FIGS. 8 to 11 show modifications of the torsion bar of the diving board of FIG. 4, said modifications each being substantially non-adjustable as to deflection rate; but being readily substituted one for another;

FIGS. 12 to 14 show further modifications of-the torsion bar of FIG. 4'where in the deflection rate of the bar may be changed;

FIG. 15 is an enlarged side elevational view in section of a means for changing the deflection rate of the bar of FIGS. 12 to 14;

FIGS. 16 and 17 are enlarged fragmentary end and side elevational views of the actuator for the deflection changing means of FIG. 15;

FIGS. 18 and 19 are, respectively, side and front elevational views of an automatic support for the deck of a diving board for use with the rate adjusting mechanism of FIG. 15; and

FIG. 20 is a rear elevational view in section and on an enlarged scale of the diving board of FIG. 4, taken approximately along line 20'-20 thereof.

Referring now to FIGS. 1 and 2 for a general descrip tion of the invention, the diving board in its preferred form is comprised of a rigid deck 20 mounted on a fixed platform 21 disposed on the edge 22 of a pool 23. Said deck can be made of any desired sheet metal material such as sheet steel, regular or stainless, or sheet aluminum or its alloy-s, but I prefer to make it from regular sheet steel which has been zinc coated for protection against corrosion. As will be hereinafter described more in detail, the deck 20 is fabricated from sheet metal in such fashion as to render it light, but rigid and strong,

so that it can be readily activated by a diver without presenting an excessive amount of inertia to be overcome by the energy-storing means used with the deck, at the same time releasing a maximum of the stored energy for use in hurling the diver into the air.

Rigid deck 20 is secured to fixed platform 21 by a hinge pin or rod 24 which passes through platform 21 and the deck 20 at the rear end of said deck. Said pin will be described in detail hereinafter in connection with FIG. 19. The energy for diving is stored in a torsion bar shown at 25 in FIG. 4, said bar being encased in a tube 26 rigidly mounted on platform 21. The bar 25 is actuated by a crank 27, one end of which is connected through a suitable ball joint 28 to an actuator 29 adapted to move wit-h deck 20* during the downward movement of said deck.

Referring now to FIGS. 1 and 3, deck 20 is comprised of a single sheet of metal 30 of substantially rectangular form, the sides of which, in the form chosen to illustrate this invention being bent downwardly to form the sides 31 and 32 of the deck. It is understood that sides 31 and 32 may be formed separately and welded or otherwise secured to sheet 30. Said sides are held rigidly in spaced relation to one another by cross members 33 to 39, inclusive, which may be welded to the sides and also to the main body of the deck to provide rigidity for the deck. The spacing of cross members 33 and 34, it may be noted, is relatively short to provide greater stiffness at the point where the weight of the diver is thrown to actuate the diving board. Similarly, cross member 35, though spaced farther from cross member 34 than said member 34 is spaced from cross member 33, is also located in a manner to provide support for the main body of the deck over the portion thereof which is to receive the impact of the diver during the actuating cycle of the diving board. The spacing of cross members 34 and 35 is additionally controlled by the fact that, as seen in FIG. 2, the sides, such as 32, are tapered at 40 toward the front end or tip of the board so that the sides at the tip provide less stiffness than they do elsewhere, and hence such lack of stiffness must be compensated for by cross members 33 and 34. The rear portion of the diving board is braced by a pair of divergent U-shaped cross members 41 and 42 welded back to back and to the underside of sheet 20 and to sides 31 and 32.

Platform 21, which constitutes the support for deck 20, is comprised of a pair of substantially identical side plates 43 and 44, which are substantially L-shaped, and which are welded to transversely extending front and rear support plates 45 and 46, respectively. Each of said support plates 45 and 46 is provided with an outwardly extending base flange 47 and 48, respectively, upon which the entire diving board rests and by which said board may be secured, if desired, to an appropriate fixed foundation at the edge of a pool.

The extra stresses imposed upon side plates 43 and 44 by hinge rod 24 are taken by plates 49 and 50 secured to the outside surfaces of side plates 43 and 44, said plates 49 and 50, for illustrative purposes, being shown as rectangular in form, with the long dimension disposed vertically to provide maximum rigidity and support for the side plates in the direction in which the forces are impressed thereon.

Transverse support plate 45 has welded thereto, and in proximity to side plate 44, a plate 51, the function of which is to support the front end of tube 26. Plate 51 is accordingly formed with an opening through which said tube 26 passes and at which said tube is welded or otherwise secured to plate 51. The rear end of tube 26 passes into an opening 52 in transverse support plate 46 at which point it is welded to said plate 46. The front end of tube 26 supports a bushing 53 in which is rotatably mounted a sleeve 54 functioning as a shaft for crank 27 to which it is secured by welding or otherwise. Said crank 27, as viewed in FIGS. and 6, has a rectangular opening 55 in which is slidably received the front end of the torsion bar 25. Said torsion bar in the form chosen to illustrate this invention is rectangular in cross section and its rear end is received in a rectangular opening 56 in a machined cap 57 for tube 26, said cap being welded or otherwise rigidly secured to transverse support plate 46. In the form chosen to illustrate this invention, said opening is larger than the cross section of torsion bar 25, and the difference in the cross sections of the torsion bar and opening is made up by a rectangular shim 58 inserted in the opening around torsion bar 25. Both shim 58 and torsion bar 25 are held against axial movement in tube 26 by a set screw 59. A rubber snap-on cap 60 is used to cover the exposed end of both the cap 57 and torsion bar 25 to protect them from corrosion.

The inside diameter of sleeve 54 is greater than the diagonal dimension across the corners of torsion bar 25, so that said bar is free to twist in sleeve 54. Said sleeve 54 is held against axial movement in tube 26 by a threaded pin 61 received in a suitable reinforced opening in tube 26 and extending into a groove 62 in the outer surface of sleeve 54. Thus said sleeve 54 may rotate within bush ing 53, and bushing 53 and said sleeve are held against axial movement relative to tube 26 by pin 61.

It may be apparent from the description thus far given that when crank 27 is oscillated about the axis of torsion bar 25, said torsion bar, because its rear end is fixed in cap 57 against rotation relative to transverse support plate 46, will be strained and will function as a torsion spring. Such springs, it has been demonstrated, have a large capacity for the storage of energy and hence provide an efficient means for supplying the resilience needed in the downward movement of rigid deck 20.

The transmission to crank 27 of the downward force imparted to deck 20 by the diver, is effected by actuator 29, which may be in the form of a rigid rod having, at one end, a ball 63 received in a socket 64 secured to the free end of crank 27 and forming the aforementioned ball joint. At its upper end actuator 29 is secured to a disc 65 which is free to rock in a cylinder 66 secured to reinforcing weldments 67, 68, 69 and 70, the latter two extending longitudinally of the deck 20 and being secured at their ends to cross members 36 and 37. The upper end of cylinder 66 is closed by a rubber pad 71, and the lower end 72 is flared so that as deck 20, on its return from an upward movement, moves downward relative to disc 65, said disc can readily find its way back into the cylinder because of the guiding action of said flared opening. The downward movement, in response to a jump by the diver, is arrested by soft pad 71 to avoid excessive noise and wear. The upward thrust produced by actuator 29 upon deck 20 when a diver jumps upon said deck, is taken by a rigid plate 73 extending from cross member 36 to cross member 37 immediately below and in contact with the sheet metal cover 30 of deck 20, and over the edges of weldments 67 and 68, as well as over the cylinder 66.

It is contemplated that deck 20, when depressed by a diver to its maximum extent, will not be lowered beyond the position shown in dot-dash lines in FIG. '7. Accordingly, the torsion bar 25 is selected to have a spring rate, that is, a deflection per unit of force, which is such as to enable the heaviest and strongest diver in the locality where the board is to be installed, to use the board without exceeding the maximum permissible deflection. In the downward movement of the deck, pressure is exerted upon actuator 29 by the disc 65 through pad 71 and plate 73, and actuator 29 then transmits the force through ball joint 28 to crank 27 and thence to the forward end of torsion bar 25. Since the rear end of said bar is prevented from turning, said bar will be twisted or placed in torsion by the actuation of crank 27 and will resist the downward movement in the characteristic fashion of a torsion spring. The energy imparted to said torsion bar 25, while said bar is twisted, is then released to cause crank 27 to reverse its direction and push upward upon actuator 29 and thus to throw deck 20 upward along with the diver. It is contemplated that disc 65 will be loose relative to the inner walls of cylinder 66 to insure a transfer of a maximum of the released energy of bar 25 to deck 20. Noise produced by sideward movement of disc 65 against cylinder 66 is reduced by a rubber O ring 74 which encircles said disc 65 between the disc and cylinder.

Should the torsion bar 25 break, or should it be desired to replace it with one of a different deflection characteristic, such change can be effected quickly by removing cap 60, backing off set screw 59 to release torsion bar 25 for :axial movement in tube 26 and then by pushing on the forward end of the torsion bar until it can be grasped at its rear end and removed from tube 26. The new bar can then be inserted into the shim 58 and into tube 26 through sleeve 54 and into the opening in crank 27. If the new torsion bar is to have a different characteristic it may have a different cross section, in which case shim 58 may be replaced by another shim. It is contemplated, however, that no shims will be used at the crank 27 and that if a different rigid torsion bar is used as a replacement, a crank having an opening to fit the replacement bar will be substituted for crank 27 Because of the relative movement between sleeve 54 and bushing 53, it is desirable to fill tube 26 with oil. Accordingly, a fill opening 99 is formed in an appropriate boss in tube 26 and said opening is closed with a plug 100. The loose fit between the forward end of torsion bar 25 and the opening 55 in crank 27 is sealed against loss of oil from within tube 26 by a nipple 101 welded to crank 27 concentrically with torsion bar 25, and closed by a plug 102. Rubber cap 60 at the rear end of torsion bar 25 performs an additional and similar seading function which serves to prevent oil from escaping from tube 26 at that end.

The adaptability of the foregoing torsion bar spring support for accommodating bars of different characteristics is demonstrated in FIGS. 8 and 9. In these figures it will be apparent that substantially all elements of the spring system are the same except the cross section of the bars 75 and 76, which require, respectively, different rectangular shims 77 and 78. Thus, if the diving board is to be used in a locality where heavy divers are active, the greater cross section torsion bar 75 will be used. If, however, the diving board is to be used in a childrens pool, then a lighter torsion bar 76 will be used in place of the heavier one 75, or the one shown at 25 in FIG. 4.

In FIG. 10 is shown a torsion bar which is made up of sections having different sized cross sections so that both children and adults can use the board and each diver will be hurled by the board as though the board .were designed specifically for him. Thus, the bar has a section 79 at the forward end connected to crank 27 and a section 80 of greater cross section than section 29 at its rear end, said section 80 having its rear end 81 received non-rotatively in a tube 82, said tube 82, in turn, being welded to a plate 83 fastened to a cap 84 corresponding to cap 57. Said section 80 is free to rotate in cap 83 so that not only is the torsion of sections 79 and 80 available, but that in tube 82 is likewise available in addition and serially to the effects of sections 80 and 79 .to give the effect of an extremely long torsion bar. Obviously various lengths of sections 79 and 80 may be used to give different characteristics to the action of the diving board, but in each case the thinner or smaller section 79 will, to all intents and purposes, take the major portion of the torsion for the lighter divers while the torsion in the portions 80 and 82 is available should the torsion impressed upon the section 79 by the heavier divers exceed that available in section 79 alone. It is understood that the two sections 79 and 80 are connected by a coupling 85 which may be provided with appropriate set screws 86 and 87 to prevent axial movement of the sections 79 and 80 relative to coupling 85.

FIG. 11 shows a modification of the torsion bar system wherein the platform shown in FIGS. 1 to 4 inclusive is available for torsion bar springs of greater length than spring 25. This arrangement is similar to that shown in FIG. 10, except that the torsion bar spring 88 in FIG. 11 is of constant section and tube 82 may or may not be a part of the torsion spring system. Obviously, tubes 82 of various lengths may be secured to cap 57 to accommodate torsion bars of greater or lesser lengths than torsion bar 88.

In the forms shown in FIGS. 12, 13 and 14, adjustability of spring rate is attained by changing the effective length of the torsion bar. Thus the torsion bar is shown at 89 and is slidably received in the square opening 90 in crank 27. Its opposite end is received in a rectangular socket 91 in a coupling 92 secured to one end of a rectangular bar 93. It is contemplated that bar 93 is rigid and will not provide any torsional spring action. Said bar 93 is received in the rectangular opening 56 in cap 57. The position of torsion bar 89 in tube 26 for maximum utilization of the resilience of the torsion bar is shown in FIG. 12. In this figure, socket 92 is drawn to the extreme left of tube 26 as viewed in FIG. 12, thereby utilizing the maximum length of the torsion bar 89 between crank 27 and coupling 92.

When it is desired to reduce the resilience of the torsion bar, that is, to increase its rate, bar 93 is pushed into tube 26 by increments while the spring board is used by the diver until the proper or desired spring action is achieved. The opposite end of torsion bar 89 merely extends under the diving board and is not at all in the way. This is shown in FIG. 13. In the form shown in FIG. 12, a longer plugged nipple .(not shown) must be used than is shown in FIG. 4 to accommodate the maximum excursion of bar 89 to the right as received in FIG. 12.

Axial adjustability of the spring using a double torsion spring is illustrated in FIG. 14. In this figure, in-' stead of the non-resilient bar 93, a torsion bar 94 is coupled through a coupling 95 similar to coupling 92 to a second torsion bar 96 appropriately received in the squared opening 97 in crank 27. Adjustability of spring characteristic is attained by pushing spring 94 axially toward crank 27, the opposite end of the torsion bar 96 again merely protruding under the diving board where it is not in the way. Different sizes of torsion bars 94, that is, different cross sections of said bar 94, may be used merely by inserting a square shim 98 in the opening 56 in the cap 57 as desired.

A convenient means for moving a torsion bar axially in the systems shown in FIGS. 12-14 is shown in FIGS. 15- 17. In these figures, the rigid bar 93 is shown as having a gear tooth rack 103 formed in its upper surface, said rack being engaged by a pinion 104 secured to a shaft 105 extending transversely of platform 21 to one side thereof. Bar 93 is protected from the elements by a sealed housing 106 welded to a rectangular plate 107 which is removably secured to a second plate 108 fastened by screws to cap 57. A bearing 109 on the side of housing 106 serves to support shaft 105. On the free end of shaft 105 is secured a drum 110, the outer surface of which is covered with a friction material 111 such as rubber.

It is contemplated that a diver will change the rate of torsion bar 89 by rotating drum lltl in increments with his foot in the appropriate direction while standing on deck 20, testing the action of the torsion bar after each increment, until the desired action is achieved. Suitable indicia (not shown) may be applied to the rubber material to show the effect to be created by rotation of the drum in a given direction.

It has been found that the weight of the unsupported portion of deck 20 on the end of crank 27 creates friction forces between the crank and bar which render difficult the axial adjustment of the bar relative to the crank. It is desirable, therefore, to remove the weight of the deck from the crank to decrease such frictional forces. An automatically operable means for accomplishing this result is shown in FIGS. 18 and 19 to which figures ref erence is now made.

Secured to weldment 69 is a spacer bar 112 to which is welded, or otherwise rigidly secured, a post 113 extending downwardly toward transverse support 45. A boss 114 is welded to transverse support 45 and is formed with an opening 115 through which passes a pivot pin 116. On said pivot pin 116 is mounted an oscillatable arm 117 which extends upwardly into proximity with post 113. A roller 118 is adapted to be contacted by a cam surface 119. Said cam surface is so shaped as to tend to push roller 118 out of the way as the arm moves downwardly with deck 20 and thus cause roller 118 and cam surface 119 to function as a detent. This action of post 113 is resisted by a spring which is centered at one end on arm 117 by a pin 121 secured to said arm and is similarly supported at its other end by an adjustable screw 122 threaded into an abutment welded or otherwise secured to a spacer 124 fixed to the back of transverse plate 45.

Movement of arm 117 by spring 123 is limited by a stop 125 in the form of a plate welded to boss 114 and extending upwardly and laterally into the path of movement of said arm 117. A rubber pad 126 may be interposed between the plate and arm to reduce noise created by the arm 117 striking against abutment 125A.

It is contemplated that the force of spring 123 will be such that the dead weight of deck 20 impressed upon roller 118 through cam surface 119 on post 113 will not be sufficient to overcome said spring 123, but that a diver, jumping upon the deck will readily cause surface 119 to cam roller 118 and arm 117 out of the way. Thus, on the upward or rebound movement of deck 20, said deck may be elevated to such an extent that post 113 is free of roller 118, at which point, spring 123 will push and hold lever 117 against abutment 125A. As the deck returns, however, cam surface 119 strikes roller 118, and although there may be some slight vibration as the post settles on roller 118, it will come to rest with post 113 supported by roller 118 rather than by the torsion bar 25. Crank 27 therefore imposes little or no torque upon torsion bar 25 and consequently there is no frictional resistance to the axial movement of torsion bar 25 through crank 27 to adjust the deflection rate of said bar. The force required to cam roller 118 out of the way is so small compared with the impact upon the deck created by a diver that the latter is not aware of the resistance of the roller.

In addition to relieving the torsion bar of the dead weight of the deck 20, post 113 and resiliently actuated roller 118 serve to dampen the vibration of the deck 20 after the deck is released by the diver and falls upon disc 65, the associated crank 27 and torsion bar spring 25.

The protection of the working parts and exposed surfaces of the diving board are among the objectives of this invention, and the manner in which these objectives are achieved in the platform 21 is shown in FIG. 20. Hinge rod 24, being subjected to friction forces produced by deck 20 which is hinged thereon, must be protected against wear as well as corrosion. It is therefore provided with bronze bushings 127, 128, upon which the sides 31, 32 are closely fitted, said sides being reinforced by plates 129, 130 around said bushings. Similar bushings 131 and 132 are used to support hinge rod 24 from said plates 43, 44 and their reinforcing plates 49, 50. Said bushings 131 and 127 have flanges 133 and 134 which abut upon one another and similarly bushings 128 and 132 have abutting flanges 135 and 136. The width of the deck 20 and the spacing between side plates 43 and 44 are so related that when the deck and bushings are assembled on hinge rod 24 there will be substantially no play between adjacent flanges. This makes possible the use of stainless steel or oil impreganted bronze bushings and the elimination of water from the working surface of hinge rod 24 within the bushings, thus providing both lubrication and protection against corrosion. The non-working surfaces of the hinge rod 24 may be painted or otherwise treated for corrosion resistance. Alternatively, said rod 24 may be made of stainless steel. Although the bushings and rod may both be made of stainless steel, which is contrary to the engineering practice of having cooperating rubbing surfaces made of dissimilar materials, I have found that an all-stainless steel construction is satisfactory in the present diving board and eliminates stains resulting from corrosion of copper alloy.

Rod 24 is held against axial movement relative to plates 129 and 130 by snap rings 137, 138. These rings are slipped over the end of rod 24 as it is pushed through one set of bushings 131, 127, for example, and after rod 24 has been pushed through bushing 128 and into bushing 132, rings 137 and 138 are snapped in place.

Wherever one plate or metal surface abuts upon or over lies another in either the deck 20 or platform 21, the covered surface is protected by a weld which extends completely around the edge thereof and prevents water from entering between the overlying or abutting surfaces. Al-l exposed surfaces are zinc coated and painted.

It may be apparent from the foregoing description that the various torsion bars may be used with diving board decks of various lengths or of the same length and the platform 21 may therefore be of standard, uniform design, regardless of the length of the deck to be used therewith. The replacement of a broken torsion 'bar is simply and economically effected. The rigid deck and platform can last indefinitely, thus reducing the expense of maintaining a diving board at a pool. If an adjustable torsion bar is used, then the deflection rate of the bar is used, a bar having the desired rate may be readily inserted in tube 26 with the aid of appropriate shims 58. It is also apparent that fixed approach decks of various lengths may be placed before and in line with deck 20, either as separate devices, or as extensions of platform 21.

It is understood that the foregoing description is merely illustrative of preferred embodiments of the invention and that the scope of this invention therefore is not to be limited thereto, but is to be determined by the appended claims.

I claim:

1. A diving board comprising a relatively fixed platform, an elongated deck, hinge means connecting one end of the deck to the platform for oscillation of the deck relative to said platform in a vertical plane, a tube disposed below said deck and fixed to said platform, a torsion bar disposed within said tube, fixed means on said platform engaging one section of said torsion bar for preventing rotation of said one section relative to said platform, a bushing in said tube, a shaft rotatably mounted in said bushing, a crank fixed to said shaft and connected to said torsion bar for rotation therewith, means responsive to the axial disposition of said torsion bar relative to the crank determining its torsional characteristics, said bar being slidable in its axial direction relative to said crank to thereby change its torsional characteristics, an actuator for said crank connected to said crank, and means connecting the deck to the actuator at a location on the deck removed from said hinge means, whereby oscillation of said deck produces a torsional strain in said bar.

2. A diving board as described in claim 1, characterized further by means sealing the torsion bar in said tube, and a fill opening in said tube for filling said tube with a lubricant.

3. A diving board as described in claim 1, said platform comprising spaced side plates and spaced end plates, said end plates being rigidly secured to said side plates, one of said end plates having an aperture to receive an end of said tube, said fixed means engaging one section of said torsion bar comprising an apertured cap secured to said one of said end plates and received in said aperture in said one of said end plates, said one section of said torsion bar being non-rotatively received in the aperture in said cap, and means for sealing said apertured cap.

4. A diving board as described in claim 1, characterized further by means sealing the torsion bar in said tube, said sealing means comprising a tubular extension on the crank for the torsion bar, and removable means closing the end of said tubular extension.

5. A diving board as described in claim 1, and means on the platform and deck for supporting said deck from the platform independently of said crank, crank actuator and the means connecting the deck to the actuator.

6. A diving board as described in claim 1, and means on the platform and deck for supporting said deck from the platform independently of said crank, crank actuator and the means connecting the deck to the actuator, said supporting means comprising resiliently engageable detent means interposed between the deck and platform.

7. A diving board as described in claim 1, characterized further by a downwardly extending post on the deck disposed forwardly of said hinge means and having a downwardly directed cam surface thereon, a roller below said cam surface adapted to engage the cam and to be moved out of the way of the post by the cam as the deck moves downwardly, and resilient means holding the roller against the cam surface in supporting relation thereto.

8. A diving board as described in claim 1, said means connecting the deck to the actuator comprising a downwardly directed cylinder on the underside of said deck, a disc secured to said actuator and received in and guided by said cylinder, and means in said cylinder and adapted to be contacted by said disc for absorbing shock produced by relative movement of the disc and the deck toward one another.

9. A diving board as described in claim 1, said fixed means on said platform engaging one section of said torsion bar for preventing rotation of said one section relative to said platform comprising a cap extending across said tube and non-rotatively secured to said platform, said cap having an opening therein to receive said torsion bar, said cap opening and said torsion bar having close-fitting non-circular cross sections.

10..A diving board as described in claim 1, said fixed means on said platform for preventing rotation of said torsion bar relative to said platform comprising a rigid bar, a non-rotatable coupling connecting one end of the torsion bar to said rigid bar, a cap extending across said tube and non-rotatably secured to said platform, said cap having an opening therein to receive said rigid bar,

said rigid bar and cap opening having close-fitting noncircular cross sections.

11. A diving board as described in claim 10, said rigid bar being free to slide axially in said cap opening to change the effective length of the torsion bar between the crank and said fixed means on said platform engaging one section of said torsion bar.

12. A diving board as described in claim 10, said rigid bar being free to slide axially in said cap opening to change the effective length of the torsion bar between the crank and said fixed means on said platform engaging one section of said torsion bar, and means on the platform for sliding said rigid bar as aforesaid.

13. A diving board as described in claim 10, said rigid bar being free to slide axially in said cap and extending rearwardly of said cap, a gear rack formed on said rearwardly extending bar, a housing for said rear- War-dly extending bar secured to said platform, a pinion gear in the housing engaging said rack, a shaft for said pinion extending through said housing, and a manually operable drum on said shaft disposed exteriorly of said housing and along side of said deck for turning said shaft and pinion.

14. A diving board as described in claim 1, said fixed means on said platform for preventing rotation of said one section of said torsion bar relative to said platform comprising a cap extending across said tube and non-rotatably secured to said platform, said cap having an opening therein through which said torsion bar extends, and a shim in said opening in the cap contacting the torsion bar.

15. A diving board as described in claim 1, said torsion bar being comprised of a plurality of torsion bars of different cross sections, and a rigid coupling connecting adjacent torsion bars together in coaxial relation to one another.

16. A diving board as described in claim 1, and means for normally preventing longitudinal movement of the torsion bar in the tube.

References Cited UNITED STATES PATENTS 1,141,515 6/1915 Alvey. 2,590,563 3/1952 Nightingale 272-66 2,606,020 8/ 1952 Anderson 267-57 2,606,759 8/1952 Colby 267-57 3,155,037 11/1964 Haskin.

ANTON O. OECHSLE, Primary Examiner. RICHARD C. PINKHAM, Examiner. A. W. KRAMER, Assistant Examiner. 

1. A DIVING BOARD COMPRISING A RELATVELY FIXED PLATFORM, AN ELONGATED DECK, HINGE MEANS CONNECTING ONE END OF THE DECK TO THE PLATFORM FOR OSCILLATION OF THE DECK RELATIVE TO SAID PLATFORM IN A VERTICAL PLANE, A TUBE DISPOSED BELOW SAID DECK AND FIXED TO SAID PLATFORM, A TORSION BAR DISPOSED WITHIN SAID TUBE, FIXED MEANS ON SAID PLATFORM ENGAGING ONE SECTION OF SAD TORSION BAR FOR PREVENTING ROTATION OF SAID ONE SECTION RELATIVE TO SAID PLATFORM, A BUSHING IN SAID TUBE, A SHAFT ROTATABLY MOUNTED IN SAID BUSHING, A CRANK FIXED TO SAID SHAFT AND CONNECTED TO SAID TORSION BAR FOR ROTATION THEREWITH, MEANS RESPONSIVE TO THE AXIAL DISPOSITION OF SAID TORSION BAR RELATIVE TO THE CRANK DETERMINING ITS TORSIONAL CHARACTERISTICS, SAID BAR BEING SLIDABLE IN IT AXIAL DIRECTION RELATIVE TO SAID CRANK TO THEREBY CHANGE ITS TORSIONAL CHARACTERISTICS, AN ACTUATOR FOR SAID CRANK CONNECTED TO SAID CRANK, AND MEANS CONNECTING THE DECK TO THE ACTUATOR AT A LOCATION ON THE DECK REMOVED FROM SAID HINGE MEANS, WHEREBY OSCILLATION OF SAID DECK PRODUCES A TORSIONAL STRAIN IN SAID BAR. 